外源物质外排泵 P-糖蛋白在胃肠道顶膜上高度表达，调节细胞内底物的水平。 P-糖蛋白在疾病中发生改变，但调节 P-糖蛋白水平的机制仍在探索中。分子运动肌球蛋白 Vb (Myo5b) 将不同的货物运输至肠上皮细胞的顶膜。我们假设 Myo5b 负责将 P-糖蛋白递送至肠细胞顶膜。我们使用多种缺乏功能性 Myo5b 或肌球蛋白结合伴侣 Rab11a 的小鼠模型来分析 P-糖蛋白定位。对猪和人体组织进行分析，以确定 MYO5B 突变背景下的 P-糖蛋白定位。使用肠类器官来检查 P-糖蛋白运输并测定 MYO5 被抑制时 P-糖蛋白的功能。在缺乏 Myo5b 或结合伴侣 Rab11a 的小鼠中，P-糖蛋白运输不当，并且在肠上皮细胞刷状缘中的存在减少。对缺乏功能性 Myo5b 的猪模型和来自具有 Myo5b 失活突变的患者的人体活检进行的免疫染色也显示肠道 P-糖蛋白的定位发生了改变。表达无动力 MYO5B 尾部结构域的人肠道类器官与 P-糖蛋白共定位，证实 P-糖蛋白在人肠细胞中由 MYO5B 运输。在人肠细胞系和类器官中抑制 MYO5 会导致 P-糖蛋白能力下降。此外，在人结肠癌细胞中抑制 MYO5 会降低 P-糖蛋白活性，并增加化疗药物引起的细胞死亡。总的来说，这些数据表明，Myo5b 对于 P-糖蛋白的顶端递送是必需的。版权所有 © 2024 AGA Institute。由爱思唯尔公司出版。保留所有权利。

The xenobiotic efflux pump P-glycoprotein is highly expressed on the apical membrane of the gastrointestinal tract, where it regulates the levels of intracellular substrates. P-glycoprotein is altered in disease, but the mechanisms that regulate the levels of P-glycoprotein are still being explored. The molecular motor myosin Vb (Myo5b) traffics diverse cargo to the apical membrane of intestinal epithelial cells. We hypothesized that Myo5b was responsible for the delivery of P-glycoprotein to the apical membrane of enterocytes.We used multiple murine models that lack functional Myo5b or the myosin binding partner Rab11a to analyze P-glycoprotein localization. Pig and human tissue were analyzed to determine P-glycoprotein localization in the setting of MYO5B mutations. Intestinal organoids were used to examine P-glycoprotein trafficking and to assay P-glycoprotein function when MYO5 is inhibited.In mice lacking Myo5b or the binding partner Rab11a, P-glycoprotein was improperly trafficked and had decreased presence in the brush border of enterocytes. Immunostaining of a pig model lacking functional Myo5b and human biopsies from a patient with an inactivating mutation in Myo5b also showed altered localization of intestinal P-glycoprotein. Human intestinal organoids expressing the motorless MYO5B tail domain had colocalization with P-glycoprotein, confirming that P-glycoprotein was trafficked by MYO5B in human enterocytes. Inhibition of MYO5 in human intestinal cell lines and organoids resulted in decreased P-glycoprotein capacity. Additionally, inhibition of MYO5 in human colon cancer cells diminished P-glycoprotein activity and increased cell death in response to a chemotherapeutic drug.Collectively, these data demonstrate that Myo5b is necessary for the apical delivery of P-glycoprotein.Copyright © 2024 AGA Institute. Published by Elsevier Inc. All rights reserved.